Crankcase for a piston machine

Abstract

In a crankcase for a piston machine having a bearing support structure for a crankshaft main bearing with a bearing base part integrally formed with the bearing support structure and a bearing cover mounted onto the bearing base part by bearing bolts extending into bolt mounting columns, the bearing support structure includes a transverse wall which extends between the crankcase walls, the bearing support base and the bearing base part and includes a rib structure of an increased wall thickness formed between the bearing base part and the bearing support base and having a recess in the area between the end of a mounting bolt bore in the bolt mounting column and the bearing support base providing for a force flux path which istributes the force flux evenly over the length of the threaded mounting bolt bore area.

What is claimed is: 
     
       1. A crankcase for a piston machine having a bearing support structure providing support for a crankshaft main bearing divided along a separation plane with a bearing base part integrally formed with said bearing support structure and a bearing cover mounted onto said bearing base part by bearing bolts extending at opposite sides of said main bearing into threaded bores of bolt mounting columns, said bearing support structure including a crankcase wall extending beyond the separation plane of said main bearing and a transverse wall extending between said bearing base part, said crankcase wall and a bearing support base of said machine, said transverse wall including a rib structure formed on said transverse wall by an increased wall thickness and extending on said transverse wall between said bearing base part and said bearing support base, said rib structure including said bolt mounting columns and having formed therein recesses extending between the end of said mounting bolt bore and said bearing support base. 
     
     
       2. A crankcase according to claim 1, wherein said threaded bore of said bolt mounting column extends in said rib structure in a direction toward said bearing support base. 
     
     
       3. A crankcase according to claim 1, wherein said rib structure becomes wider toward said bearing base part and joins the bearing base part from the bearing separation plane over an angular area of 50° to 80°. 
     
     
       4. A crankcase according to claim 3, wherein the opposite sides of said rib structures are widened along the longitudinal extension of said rib structures in the form of convexly shaped arcs. 
     
     
       5. A crankcase according to claim 1, wherein said recesses at opposite sides of said rib structure have the same shape and are disposed opposite one another and form at opposite sides of said recesses opposite rib legs. 
     
     
       6. A crankcase according to claim 1, wherein said recesses have essentially the shape of a drop with a pointed end disposed adjacent said bearing support base and a rounded end adjacent to the bearing base part. 
     
     
       7. A crankcase according to claim 5, wherein a wall remains at the bottom of said recesses which is disposed essentially in a common plane with said transverse wall. 
     
     
       8. A crankcase according to claim 7, wherein said wall disposed in said recesses has a thickness which is not greater than that of said transverse wall. 
     
     
       9. A crankcase according to claim 7, wherein said recesses have at least at the opposite pointed and rounded ends inclined side walls providing for a smooth diameter transition from the ribs to the recess bottom wall. 
     
     
       10. A crankcase according to claim 6, wherein said transverse wall includes several webs projecting essentially to the level of the rib structure and extending between said rib structure and said crankcase wall. 
     
     
       11. A crankcase according to claim 10, wherein an upper web extends essentially at the level of the rounded end of said recess, an intermediate web extends essentially along the separation plane of said divided main bearing adjacent to said bolt mounting column, and a lower web extends between the end of said intermediate web adjacent said bolt mounting column and the bottom end of said crankcase wall. 
     
     
       12. A crankcase according to claim 1, wherein, between said rib structures at opposite sides of said bearing base part, an oval opening is provided in said transverse wall so as to extend in a direction normal to the separation plane of said divided main bearing. 
     
     
       13. A crankcase according to claim 1, wherein said bearing support structure is symmetrical with respect to its center axis which extends normal to the separation plane of said main bearing. 
     
     
       14. A crankcase according to claim 1, wherein said bearing support structure is a structure formed as an integrally cast component of said crankcase.